Investigation of Gain in Bismuth Doped Fibre Considering ASE under 830 nm Pump

Abstract

In this study, effect of amplified spontaneous emission (ASE) on gain characteristics of bismuth doped fibre (BDF) is investigated at 830 nm pump wavelength. Finding the efficient length of the fibre and suitable pumping conditions are examined. Using BDF up to 15 m of length it is observed that the pump power does not affect the gain much after saturation of gain; but increases both, forward and backward ASE. However, reduced effect of ASE can be found from using a larger pump power. For BDF of 5 m length under 830 nm pump, the gain difference is fluctuated due to the effect of ASE until 120 mW of pump power, and then it jumps up. Besides, in presence of ASE the gain difference moves up until 120 mW of pump power for the BDF length of 10 m and 15 m, and then it moves downward. Hence, it is suitable to use 10 m length of fibre with pump power of 300 mW; the 5 m of fibre length cannot be used because of an upward gain difference due to the effect of ASE with increasing pump power. For all the cases, signal power increases ASE and that hampers the gain to be declined. Lastly, the gain performance of BDF is compared and found much smaller than that of erbium doped fibre (EDF).